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Anything is possible. But you are talking about a lot of work and if you get wires messed up or crossed it could become frustrating very fast. Have you checked into updating the 73 with a after market one before you go and get one from a 89 ?
My 74 has glass fuses it doesn't bother me. I just keep an assortment in the glove box since most gas stations out here don't have them anymore. Unless your harness is butchered beyond repair, I'd just leave it alone.